FIG. 12 shows a mounting apparatus for electronic components which comprises a machine frame 50 provided with a transport rail 51 for printed boards 12, a drive mechanism 3 mounted on the machine frame 50 and comprising an X-axis table 52 and a Y-axis table 53, and a suction head 54 movable by the drive mechanism 3 in an X-axis direction and a Y-axis direction. The suction head 54 includes a suction nozzle 1 which is rotatable about a Z-axis by a rotating mechanism incorporated in the suction head 54.
The component mounting apparatus described is adapted to move the suction head 54 to a component feed station 55 by the drive mechanism 3, cause the suction nozzle 1 to hold a component 11 attracted thereto, thereafter move the component 11 to a specified position above the printed board 12, further cause the rotating mechanism to change the orientation of the component 11 and then mount the component 11 on the printed board 12.
To position the component 11 in place when it is to be mounted on the printed board 12, the following methods have heretofore been used.
With reference to FIG. 13, an image of the component 11 as held by the suction nozzle 1 on a head body 8 is taken by one of two cameras 30, 31, i.e., by the camera 30, and an image of the position 13 where the component is to be mounted on the board 12 (mounting position) is taken by the other camera 31. The position of the component 11 held by the suction nozzle 1 and the mounting position 13 on the board 12 are detected based on the resulting image signals from the two cameras to correct the difference between the two positions.
FIG. 14 shows another arrangement wherein a half mirror 32 is rotatably provided between the printed board 12 and the component 11 as held attracted to the suction nozzle 1 and positioned above the printed board 12, and a camera 34 is disposed as opposed to the direction of reflection from the mirror 32 with an optical lens 33 interposed between the camera and the mirror. The lens 33 is housed in a lens barrel 35, which further has a shutter mechanism, barrel drive mechanism, etc. (not shown) incorporated therein. An image of the component 11 held by the suction nozzle 1 and an image of the mounting position on the printed board 12 can be taken by the camera 34 at the same time when the half mirror 32 is rotated. The position of the component 11 is matched to the mounting position based on the image signals from the camera 34 (Unexamined Japanese Patent Publication HEI 3-217095).
FIG. 15 shows another arrangement wherein two cameras 36, 37 are vertically attached to a suction head body 8. The two cameras 36, 37 first take images of corners of the component 11 as held by the suction nozzle 1 and positioned above the printed board 12, and then take images of the mounting position 13 with the component 11 rotated through 45 degrees. The position of the component 11 and the mounting position 13 are subsequently detected based on the image signals from the cameras 36, 37 to obtain a match between the two positions (Unexamined Japanese Patent Publication HEI 1-321700).
However, the conventional techniques described have the following problems. With the technique of FIG. 13, the component 11 is horizontally moved toward the printed board 12 and mounted thereon, after the position of the component 11 has been detected from the image taken thereof, so that the movement results in a new deviation, which makes it impossible to achieve a high mounting accuracy,
With the technique of FIG. 14, the lens barrel 35 has the shutter mechanism, barrel drive mechanism, etc. incorporated therein and is therefore complex in construction. Further in the case of the technique of FIG. 15, the images of the component 11 and the mounting position 13 can not be taken within one picture frame at the same time. Accordingly, there arises a need to rotate the component 11 as stated above for taking the images of the mounting position 13, giving rise to the problem that acceptance of the image signals takes time.
Also proposed are other contrivances such as a transparent suction head body (Examined Japanese Patent Publication SHO 62-13152) and a suction head body which has a bent shape to avoid interference with the camera to be positioned above the component (Unexamined Japanese Patent Publications SHO 63-122300 and SHO 62-154700), whereas these suction heads are complex in construction and are not suited to actual use.